I'm a volunteer fire fighter for Timberline Fire and Nederland Fire. These are large rural district up in the mountains of Colorado. We usually use paper maps, because of poor to nonexistent cell phone connectivity.
Where I live, there isn't any dependable cell service, so offline mapping is mandatory. Paper maps have a few advantages, it's easier for a group of people to look at a map together than it is on a GPS. Also paper maps don't have problems with battery life. We cover several hundred square miles, most of it national forest or mountain wilderness area.
Old-timers in my department of course know everywhere and everything. :-) But new fire fighters have a huge learning curve. We have many "community trails", and campsites, ie... not on any map. That and specialized locations useful to us, like water sources, or helicopter landing zones.
I've been into offline digital mapping for a long-time, but these days the technology has gotten much better. Gone are the days I had to use a physical GPS device attached to my laptop, plus sufficient battery storage to last long enough to be useful. There's been a few times I got saved on trips because I had this capability. Like finding the nearest gas station when lost in the wilds of Tasmania. Yes, my co travelers on that trip were very happy when we pulled into the only gas station for a long way.
Another time we were lost in Albania on a speaking tour at Universities, cause there were no maps allowed, and there weren't many street signs either. Google maps would cache a few tiles if you were careful, and conveniently, many gas stations and restaurants in Albania have wifi service. So we were saved.
These days though the tools for offline mapping are great. With sufficient disk storage and a decent processor, you can make your own maps with whatever custom data you want. As a fire fighter and climber, (and convieniently software engineer) I focus on the areas we respond to, local campgrounds, backcountry trails, climbing or skiing accidents. Along with that water sources are really important to us, as we have few fire hydrants, and we often use helicopters for medical emergencies.
I'll go into the tech details on another page, but the brief summary is I'm using Open Street Map data I've got running in a local postgres database, and wrote my own utilities for data format conversion. One of the big problems I've had is that all of the websites that convert GIS files have limits on size, any my files were way larger. That and the various open source programs had issues with supporting all the same versions of each format, so details were getting lost. Finally I wanted something that could generate offline maps that looked as nice as the online ones. So all trails, ski runs, etc... are color coded as to difficulty. Colors and icons are key to getting useful data from the phone or tablet efficiently, as they clue the eye into the details you want. Very useful when responding fast.
Part of the trick of making maps that run well on a mobile device is reducing the data sets to a small and focused subset. The various categories of locations can be toggled on and off for clarity, and to reduce screen clutter. But each location is still searchable.
There are two parts to a mobile map, the basemap and the data files. The basemaps are usually specific to the GPS application used to display them. The data files (KML or KMZ) are portable across a wide range of applications, like Google Earth or Google Maps. As I improve my software, I update many of these files. The PDFs are GeoPDFs, and the TIFs are GeoTiff for Avenza.
Most rural volunteer fire departments don't barely have IT support, much less any money... I've been producing custom digital maps for the local rural fire districts here in the Colorado Rockies. Multiple fire departments around here have gone to mounting tablets in fire apparatus to work as a dedicted mapping device. You can download this data from my Fire Districts page.
I travel quite a bit for work and climbing, so here's a few basemaps and KMZ data files for some of those areas.